Linerless container closure

Claim 1

A one-piece, linerless, plastic cap for a container having a generally cylindrical neck portion comprising: a. an annular top wall portion, said top wall having a shallow cylindrical recess in the underside thereof, said recess defined by a planar bottom wall and an inwardly facing, cylindrical shoulder; b. an integral, generally cylindrical skirt section depending from said top wall section, said skirt section joining said top wall section outwardly of said cylindrical recess thereby providing a downwardly facing shoulder portion on said sidewall interior; c. engaging means on the interior wall of said skirt portion adapted to engage retaining means provided on the exterior wall of said neck portion of said container; d. a single, integral, flexible, annular, sealing ring provided on the underside of said top wall and having its proximate end integrally attached to said top wall section at the intersection of said planar bottom wall and said inwardly facing cylindrical shoulder and its distal end projecting downwardly and inwardly, said ring making sealing contact with the rim of said neck portion and the upper end of said neck portion being closely received within the lower portion of said cylindrical recess when said cap is secured to said container neck.